The present invention relates to a new and improved construction of a controlled deflection roll, sometimes referred to in the art as a roll with bending or sag compensation.
Generally speaking, the controlled deflection roll of the present development is of the type comprising a stationary roll support or core and a roll shell rotatable about the stationary roll support. The roll shell itself is rotatably mounted at its ends at the roll support in a bearing or support arrangement. At least one pressure or support element is located between the roll support and the roll shell. By means of this pressure or support element the roll shell is rotatably supported at the roll support, and the pressure element is effective, with its supporting force, in a force direction which passes through a pressure plane extending through the lengthwise axis of the roll shell.
One such type controlled deflection roll has been taught to the art, for instance, from U.S. Pat. No. 3,802,044, granted Apr. 9, 1974. With this construction of controlled deflection roll, which has been found to be quite satisfactory in practice, there are provided as the pressure or support elements pistons or punches subjected to a hydrostatic contact pressure and simultaneously forming a hydrostatic bearing with the inner surface of the roll shell. The pistons can all be impinged with the same hydrostatic pressure, or different pressures can act upon groups of such pressure elements or even individual ones of such pressure elements.
It has been found that with a controlled deflection roll of this type, during its assembly into a rolling mill, the danger exists of fracturing the roll shell when the hydrostatic pressure or support elements are impinged with a pressure while there is absent any counter support roll or the surface of such pressure elements is spaced too far from the roll shell. For instance, this situation can arise after regrinding the roll shell of a rolling mill.